The plot is a bit silly, yes, but then so are many DW plots! But the whole genre of that era's detective fiction is so expertly parodied that I can forgive that and just enjoy the send-up!

I think that Fenella Woolgar was perfect casting as Agatha - DT's idea; the interplay between them all was wonderful, but David and Catherine together just eat up the screen, don't they? I'm a bit sad we didn't get a bit more of that :(